构建健康检查编排器

项目概述

本项目实现一个面向 composite health checking 的完整系统，核心要解决的问题是 rolling up many dependency checks into one health verdict without a single slow check blocking the answer。整体由 Check registry、Parallel runner、Timeout guard、Rollup policy、Status cache 五个模块组成，每个模块单一职责、可独立测试，最后通过集成测试验证端到端正确性。设计上把 a dependency check that hangs indefinitely and degrades the health endpoint into a timeout for every caller 作为第一类需求先行处理，而非事后再补。

架构与关键决策

数据模型为 a registry of named checks each with a timeout, run in parallel and rolled up into an overall status with a short cache。Check registry 定义其余阶段共同依赖的数据形状并在边界处校验输入；Parallel runner 承载 composite health checking 的正确性逻辑；Timeout guard 专门处理 a dependency check that hangs indefinitely and degrades the health endpoint into a timeout for every caller，在失败路径上给出明确的拒绝、重试或降级策略；Rollup policy 提供可观测性，每次操作输出带关联 id 的结构化事件；Status cache 在过载时按既定方式降级，避免过载演变为数据损坏。配置与代码分离，使风险变更可经 diff 审阅。

实施与测试

按五个阶段依次实现 Check registry、Parallel runner、Timeout guard、Rollup policy、Status cache，每阶段配套聚焦单测。集成测试组合各模块并驱动真实 composite health checking 场景：先验证正常路径，再刻意触发 a dependency check that hangs indefinitely and degrades the health endpoint into a timeout for every caller 并断言系统降级而非损坏。所有依赖均在进程内或被桩替换，用例在 CI 中确定可复现。

限制与后续

• 单区域设计，多区域复制超出范围。
• Check registry 默认进程内，未水平共享。
• 无鉴权层，假定部署在强制身份的边缘之后。

代码示例

# setup for health-check-orchestrator
pnpm init
pnpm add fastify p-timeout
pnpm add -D typescript tsx vitest

health_check_orchestrator/
├── src/index.ts
├── src/check-registry.ts
├── src/parallel-runner.ts
├── tests/health_check_orchestrator.test.ts
└── package.json

// Check registry: composite health checking core
export function checkregistry(input: CheckregistryInput): CheckregistryResult {
  // Build the check registry that anchors composite health checking and defines the core data shape.
  return processCheckregistry(input);
}

// Parallel runner — handles composite health checking Add the parallel runner so
export class Parallelrunner {
  constructor(private opts: ParallelrunnerOptions) {}
  async run(ctx: Context): Promise<ParallelrunnerOutput> {
    return this.execute(ctx);
  }
}

// Timeout guard: composite health checking stage
export const timeoutguard = (next: Next) => async (req: Request) => {
  const out = await transform(req);
  return next(out);
};

// Rollup policy for composite health checking
export async function rolluppolicy(stream: AsyncIterable<Chunk>): Promise<Aggregate> {
  let acc = init();
  for await (const c of stream) acc = merge(acc, c);
  return acc;
}

// Status cache: composite health checking finalization
export function statuscache(state: State): Result {
  validate(state);
  return finalize(state);
}

# run the composite health checking test suite
pnpm vitest run